1. Field of the Invention
The field of the invention relates to cellulose hydrogels and processes for their production. The field also relates to applications of cellulose hydrogels, for example, as ophthalmic materials, such as soft contact lenses and their production processes.
2. Description of the Related Art
Hydrogels are water-insoluble polymers having the ability to swell in water or aqueous solution without dissolution and to retain a significant portion of water or aqueous solution within their structure. Hydrogels possess a degree of flexibility similar to natural tissue. As such, hydrogels have many uses and applications.
Attempts have been made to improve upon various properties of hydrogels, for example, to increase strength, water content, transparency, permeability or biocompatibility properties, often with mixed results. For example, attempts have been made to optimize certain physical properties of hydrogels, such as strength, to suit various applications. However, such increases in strength often come at the expense of other properties of the hydrogel, such as transparency or water content.
There remains a need for improved hydrogels that have desirable properties, including some or all of high water content, biocompatibility, tensile strength, permeability, and transparency to support a variety of uses, including as ophthalmic materials, such as contact lenses.
This background information is provided for the purpose of making information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should it be construed, that any of the preceding information constitutes prior art against the present invention.